TiN @NiCo2O4 coaxial nanowires as supercapacitor electrode materials with improved electrochemical and wide-temperature performance

Highly active electrode materials with designed nanostructure play an important role for the application as high-performance electrochemical energy storage devices. Herein we report a facile synthesis of titanium nitride nanowire array (TiN NWA)@NiCo2O4 coaxial composite for the first time. The TiN NWA was synthetized through hydrothermal method combined with reduction and nitridation treatment. The diameter of the array is about 200 nm and the length is up to 10 μm. To improve the electrochemical properties related to energy storage, NiCo2O4 nanowires with about 20 nm in diameter and length of about 2 μm are further coated on the TiN NWA by hydrothermal method. The TiN NWA@NiCo2O4 coaxial composite displays a high specific capacitance (1200 F g−1 at current density of 2.0 A g−1), good rate capability (63.6% capacitance retention from 2 A g−1 to 100 A g−1) and excellent cycle stability (7.8% capacitance loss after 5000 cycles) in a 2 M KOH aqueous electrolyte. Moreover, the TiN NWA@NiCo2O4 composite is able to maintain stable electrochemical performance at wide temperature range of 25-65 °C.